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6. Design of telescopic nadir imager for geomorphology (TENGOO) and observation of surface reflectance by optical chromatic imager (OROCHI) for the Martian Moons Exploration (MMX)

Author

Kameda, Shingo, Ozaki, Masanobu, Enya, Keigo, Fuse, Ryota, Kouyama, Toru, Sakatani, Naoya, Suzuki, Hidehiko, Osada, Naoya, Kato, Hiroki, Miyamoto, Hideaki, Yamazaki, Atsushi, Nakamura, Tomoki, Okamoto, Takaya, Ishimaru, Takahiro, Hong, Peng, Ishibashi, Ko, Takashima, Takeshi, Ishigami, Ryoya, Kuo, Cheng-Ling, Abe, Shinsuke, Goda, Yuya, Murao, Hajime, Fujishima, Saori, Aoyama, Tsubasa, Hagiwara, Keiji, Mizumoto, Satoko, Tanaka, Noriko, Murakami, Kousuke, Matsumoto, Miho, Tanaka, Kenji, and Sakuta, Hironobu

Published
2021
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15. Design of Telescopic Nadir Imager for Geomorphology (TENGOO) and Observation of Surface Reflectance by Optical Chromatic Imager (OROCHI) for the Martian Moons Exploration (MMX)

Author

Kameda, Shingo, primary, Ozaki, Masanobu, additional, Enya, Keigo, additional, Fuse, Ryota, additional, Kouyama, Toru, additional, Sakatani, Naoya, additional, Suzuki, Hidehiko, additional, Osada, Naoya, additional, Kato, Hiroki, additional, Miyamoto, Hideaki, additional, Yamazaki, Atsushi, additional, Nakamura, Tomoki, additional, Okamoto, Takaya, additional, Ishimaru, Takahiro, additional, Hong, Peng, additional, Ishibashi, Ko, additional, Takashima, Takeshi, additional, Ishigami, Ryoya, additional, Kuo, Cheng Ling, additional, Abe, Shinsuke, additional, Goda, Yuya, additional, Murao, Hajime, additional, Fujishima, Saori, additional, Aoyama, Tsubasa, additional, Hagiwara, Keiji, additional, Mizumoto, Satoko, additional, Tanaka, Noriko, additional, Murakami, Kousuke, additional, Matsumoto, Miho, additional, Tanaka, Kenji, additional, and Sakuta, Hironobu, additional

Published
2021
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22. Coefficient of Friction in Diamond-Like Carbon Films

Author

Kanda, Kazutaka, Hashimoto, Masaki, Ishigami, Ryoya, Yasuda, Keisuke, and Iwai, Yoshiro

Subjects
ERDA, Diamond like carbon, Hydrogen content, DLC, Coefficient of friction, Friction test
Abstract

The pin-on-plate and the pin-on-disk friction test were carried out to clarify the mechanism of low friction coefficient of diamond like carbon (DLC) films. As the test piece, six kinds of commercially available DLC coated specimens were prepared. The hydrogen content of DLC was determined by elastic recoil detection analysis (ERDA) method using 2 MeV of He ion beam from the tandem accelerator. Pin-on-plate type friction test was carried out with the combination of DLC coated pin and high-speed tool steel plate. As a result of the friction test, it became clear that in the case of these combinations, all DLC show a low coefficient of friction of 0.08 - 0.09 in initial term, and it rises with time. In the case of DLC with a low hydrogen content, debris of heat-affected DLC was not observed in and around the wear truck of plate. These tendency were different from the conventional experiment that coated DLC to a plate. As a general tendency in this experiment, harder DLC film maintained lower coefficient of friction. From this result, it was estimated that DLC with low abrasion maintain high contact pressure and develop a low coefficient of friction.

Published
2011

23. Relation between Friction Coefficient and Hydrogen Contents in Diamond Like Carbon Films

Author

Kanda, Kazutaka, Kishigami, Kyohei, Hashimoto, Masaki, Ishigami, Ryoya, and Iwai, Yoshiro

Subjects
ERDA, Diamond like carbon, Hydrogen content, DLC, Friction coefficient, Friction test
Abstract

The pin-on-plate friction test was performed by using various kinds of DLC films to clarify the relation between the hydrogen content and the friction coefficient of DLC. As the test piece, twelve kinds of commercially available DLC coated specimens were prepared. Their hydrogen contents were determined by elastic recoil detection analysis (ERDA) method using 2 MeV of He ion beam from the tandem accelerator. As a result of the friction test, it became clear that the coefficient of friction tended to increase with increase of hydrogen content of DLC. By the Raman spectrum analysis, the debris adhered around the wear track were assigned as worn-out mixture of DLC and pin materials. Generation of this material was presumed to be the cause of low coefficient of friction discovery of DLC.

Published
2010

27. Polarity dependent radiation hardness of GaN

Author

Matsuo, Masayuki, primary, Murayama, Takayuki, additional, Koike, Kazuto, additional, Sasa, Shigehiko, additional, Yano, Mitsuaki, additional, Gonda, Shun-ichi, additional, Uedono, Akira, additional, Ishigami, Ryoya, additional, Kume, Kyo, additional, Ohtomo, Tomomi, additional, Furukawa, Erika, additional, Yamazaki, Yoshiki, additional, Kojima, Kazunobu, additional, and Chichibu, Shigefusa, additional

Published
2015
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28. The Evaluation of the Surface Strength of DLC Films by MSE Method

Author

IWAI, Yoshiro, primary, SAKANO, Kaoru, additional, PIAO, Zhonghui, additional, SHIBATA, Kenichi, additional, KOHATA, Mamoru, additional, KANDA, Kazutaka, additional, MIYAJIMA, Toshiro, additional, HASHIMOTO, Masaki, additional, ISHIGAMI, Ryoya, additional, and YASUDA, Keisuke, additional

Published
2014
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40. Experiments using a 200 kV implanter and a 5 MV tandem accelerator.

Author

Ishigami, Ryoya, Ito, Yoshifumi, Yasuda, Keisuke, and Hatori, Satoshi

Subjects
*ION accelerators, *DEUTERONS
Abstract

N[sup +] ions with an energy of 190 keV were implanted into an Al alloy (95% Al and 5% Mg) to a dose of 1.5 x 10[sup 19] ions/cm². A layer of AlN with 1.4 μm thickness was obtained. The amounts of InN deposited on GaAs or Al[sub 2]O[sub 3] were measured by RBS using He[sup 2+] ions with an energy of 3.14 MeV generated by a tandem accelerator. The thickness was estimated to be 0.047 μm and 0.26 μm in each case. An experiment on transmission ERDA using He[sup 2+] ions with an energy of 15 MeV is proposed for the measurement of deuterons in thick Ti foil with good depth resolution. [ABSTRACT FROM AUTHOR]

Published
2001

41. Laser cutting of thick steel plates and simulated steel components using a 30 kW fiber laser

Author

Tamura, Koji, Ishigami, Ryoya, and Yamagishi, Ryuichiro

Abstract

Laser cutting of thick steel plates and simulated steel components using a 30 kW fiber laser was studied for application to nuclear decommissioning. Successful cutting of carbon steel and stainless steel plates up to 300 mm in thickness was demonstrated, as was that of thick steel components such as simulated reactor vessel walls, a large pipe, and a gate valve. The results indicate that laser cutting applied to nuclear decommissioning is a promising technology.

Published
2016
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46. Degradation of Fe–Pt thin film permanent magnets by irradiation with 4He and H ions

Author

Ishigami, Ryoya, Batchuluun, Chuluunbaatar, and Yasuda, Keisuke

Subjects
*CHEMICAL decomposition, *METALLIC films, *PERMANENT magnets, *ION bombardment, *MAGNETIC fields, *CRYSTAL structure, *CRYSTAL lattices
Abstract

Abstract: Fe55Pt45 thin film permanent magnets having a thickness of 120nm are irradiated with 180keV 4He and 90keV H ions. In-plane and out-of-plane coercivities of the magnets are decreased to half by irradiation with the 4He ions at a fluence of 3.2×1015 ions/cm2 or with the H ions at a fluence of 5.7×1016 ions/cm2. In-plane magnetizations without a magnetic field are decreased by 10%, but out-of-plane magnetizations without a magnetic field are decreased by 90% by irradiation with the 4He ions at a fluence of 1×1016 ions/cm2 or with the H ions at a fluence of 3×1017 ions/cm2. Because their magnetizations do not recover to their original levels prior to the irradiation by re-magnetization in a magnetic field of 40kOe, it is proved that the degradation is caused by disorder of crystallographic structure. Atomic densities of the Fe and the Pt atoms displaced from their lattice sites are calculated as a function of depth by a TRIM simulation program. [Copyright &y& Elsevier]

Published
2012
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47. ERDA with 15MeV 4He ions under atmospheric pressure

Author

Ishigami, Ryoya, Ito, Yoshifumi, Yasuda, Keisuke, and Hatori, Satoshi

Subjects
*PRESSURE, *HYDROGEN, *ATMOSPHERIC pressure, *TITANIUM
Abstract

Abstract: ERDA measurements in reflection geometry have been performed on titanium deuteride (TiD x ) set in air of 1atm and titanium hydride (TiH x ) set in a mixture of hydrogen gas of 0.5atm and deuterium gas of 0.5atm. A 4He beam with an energy of 15MeV is extracted through a molybdenum foil with a thickness of 5μm into the gases. Spectra from deuterium and hydrogen in these samples are obtained by subtraction of spectra of titanium from spectra of the TiD x and TiH x , respectively. Depth profiles of the deuterium and hydrogen atoms are calculated from the obtained spectra. The atomic ratios of deuterium and hydrogen to titanium in the samples are 0.83 and 0.79 up to a depth of 8μm, respectively. [Copyright &y& Elsevier]

Published
2005
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48. Recoil Cross-Sections of Proton and Deuteron by 4He at a Recoil Angle of 0°in an Energy Range of 5–14 MeV

Author

ISHIGAMI, Ryoya, ITO, Yoshifumi, YASUDA, Keisuke, SASASE, Masato, NISHIO, Shigeru, and HATORI, Satoshi

Abstract

Differential recoil cross-sections at a 0° recoil angle in reactions for p(4He, p)4He and d(4He, d)4He were obtained from the ratios of particle counts per solid angle measured at 0°and 17.8° in the incident energy range between 5 and 14MeV, using the reference cross-sections given at 17.8°. The count ratios were determined by simultaneously detecting protons and/or deuterons that recoiled at 0°and 17.8°. Eleven cross-sections for p(4He, p)4He and seventeen cross-sections for d(4He, d)4He were newly obtained. The cross-sections of p(4He, p)4He agree well with the data reported by several authors in the 5 MeV≤.EHe≤ 14 MeV energy region. The cross-sections for d(4He, d)4He are also quite close to the reported values in both the 5MeV≤EHe≤7.5MeV and the 13MeV≤.EHe≤14MeV ranges. The present research was able to successfully yield the 0°cross-sections of d(4He, d)4He in the 9 to 11 MeV region. The errors of the proton and deuteron cross-sections were estimated to be 3.9–7.2% and 4.1–8.9%, respectively.

Published
2004
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49. Radiation hardness of single-crystalline zinc oxide films.

Author

Koike, Kazuto, Aoki, Takahiro, Fujimoto, Ryugo, Sasa, Shigehiko, Yano, Mitsuaki, Gonda, Shun-ichi, Ishigami, Ryoya, and Kume, Kyo

Abstract

Zinc oxide (ZnO) is a potential semiconductor to exhibit high radiation hardness since large threshold displacement energy for damage can be expected due to the small unit-cell volume and large bandgap energy. In order to study the radiation hardness, single-crystalline c-axis-oriented ZnO films with and without two-dimensional electron gas, and bulk crystals of ZnO and gallium nitride (GaN) for comparison, were irradiated with 8 MeV protons at the wide range of fluences from 2×1013 to 1×1017 p/cm2. For both ZnO films, decrease of luminescence intensity followed by increase of electrical resistance was observed at larger fluences than ∼5×1014 p/cm2. This threshold fluence was found to be much larger and larger than those of GaN and ZnO bulk crystals, respectively, indicating that ZnO thin films should be useful for such device applications as the electronics for space satellites and nuclear reactors. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Published
2012
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50. Ar+ion impact desorption of Cu and Ag from the Si(111)-quasi-5 × 5-Cu and CuSi(111)-√3 × √3-Agsurfaces

Author

Ishikawa, Dai, Yuhara, Junji, Ishigami, Ryoya, Soda, Kazuo, and Morita, Kenji

Abstract

The concentration changes of Cu and Ag coverages at the CuSi(111)-√3 × √3-Agand Si(111)-quasi-5 × 5-Cu surfaces by 5 keV Ar+ion bombardment have been measured by means of AES and Rutherford backscattering (RBS) techniques in order to determine the cross-sections for their desorption and recoil-implantation. We have evaluated the potential barrier heights for desorption and recoil-implantation from the obtained cross-sections. The potential barrier height for desorption of Ag adsorbates is in accordance with the sublimation energy of Ag metal, and the potential barrier height for recoil-implantation of Ag is consistent with that for the Si(111)-√3 × √3-Ag surface. Together with the observed √3 × √3 LEED pattern for the CuSi(111)-√3 × √3-Agsurface, these results suggest that Ag atoms are accommodated at the top-most surface layer as the Si(111)-√3 × √3-Ag surface. On the other hand, the cross-section for desorption of Cu is smaller than that of Ag, which leads to rather high potential barrier height, and the cross-section for recoil-implantation is considerably larger than that of Ag. For these results, we propose a hypothesis that Cu atoms are buried and located at an interstitial site in the surface layer of the CuSi(111)-√3 × √3-Agsurface. It is also found that the Si(111)-quasi-5 × 5-Cu structure is easily destroyed by Ar+ion bombardment.

Published
1996
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